Some interesting points, Chirs.
Although I tend to agree with most of what Sean & Mike & Ed have said, I don't think you can ever be too careful with vintage radios, especially if they're used by other people who might not be so aware of the theoretical risks.
For example, somebody recently left one of my 1930s mains sets on for hours at a time while they went out, as a burglar deterrent, which I personally feel is a bit risky.
I can still remember a neighbour's house - a subtantial, detached 1930s mock tudor place set in large grounds near Wimbledon Common which literally burned to the ground about 15 years ago, apparently the result of an electrical fault. I walked past at teatime and it looked just like it always had done, but when I went by in the evening, it was all gone, just a pile of rubble and a horrible smell
Quote:
Originally Posted by Chris55000
Transformers usually remain safe if they're not overheated due to electrolytic failures, leaky anode-to-grid couplers or shorts on dial lights! Once wax or other impregnation has stared to ooze from a mains transformer, *it is no longer safe* even if it is still running the set apparently normally.
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That's interesting. Could you explain? I have read in several places that " a little migration of wax" from mains transformers can be considered normal, and will happen even in the absence of a fault condition. I often fit those little Cliff wire-ended thermal fuses in series with the mains supply, which I assumed were a reasonable precaution against severe overheating and fire.
Quote:
Originally Posted by Chris55000
Dropping resistors:- If the cement coating has started to flake off a heater dropper in the AC/DC type set exposing the elements, again the set should be considered no longer safe to test or attempt to use
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Again, why? Is there any way to repair?
Nick.